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<div class="header">
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<a href="#func-members">Functions</a>  </div>
  <div class="headertitle">
<div class="title">warp_perspective.cl File Reference</div>  </div>
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<div class="contents">
<div class="textblock"><code>#include &quot;<a class="el" href="helpers_8h_source.xhtml">helpers.h</a>&quot;</code><br />
<code>#include &quot;<a class="el" href="warp__helpers_8h_source.xhtml">warp_helpers.h</a>&quot;</code><br />
</div>
<p><a href="warp__perspective_8cl_source.xhtml">Go to the source code of this file.</a></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:aa02a47b9dfa96a2705d5c77044a40048"><td class="memItemLeft" align="right" valign="top">const float16&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="warp__perspective_8cl.xhtml#aa02a47b9dfa96a2705d5c77044a40048">build_perspective_mtx</a> ()</td></tr>
<tr class="memdesc:aa02a47b9dfa96a2705d5c77044a40048"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the perspective matrix.  <a href="#aa02a47b9dfa96a2705d5c77044a40048">More...</a><br /></td></tr>
<tr class="separator:aa02a47b9dfa96a2705d5c77044a40048"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a2791d623c1dbcf7e7111b8ff1b7daeeb"><td class="memItemLeft" align="right" valign="top">const float8&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="warp__perspective_8cl.xhtml#a2791d623c1dbcf7e7111b8ff1b7daeeb">apply_perspective_transform</a> (const float2 coord, const float16 mtx)</td></tr>
<tr class="memdesc:a2791d623c1dbcf7e7111b8ff1b7daeeb"><td class="mdescLeft">&#160;</td><td class="mdescRight">Transforms four 2D coordinates using the formula:  <a href="#a2791d623c1dbcf7e7111b8ff1b7daeeb">More...</a><br /></td></tr>
<tr class="separator:a2791d623c1dbcf7e7111b8ff1b7daeeb"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ab8f5d79d7699ec7e2a805a25ca0fca2b"><td class="memItemLeft" align="right" valign="top">__kernel void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="warp__perspective_8cl.xhtml#ab8f5d79d7699ec7e2a805a25ca0fca2b">warp_perspective_nearest_neighbour</a> (__global uchar *in_ptr, uint in_stride_x, uint in_step_x, uint in_stride_y, uint in_step_y, uint in_offset_first_element_in_bytes, __global uchar *out_ptr, uint out_stride_x, uint out_step_x, uint out_stride_y, uint out_step_y, uint out_offset_first_element_in_bytes, const int width, const int height)</td></tr>
<tr class="memdesc:ab8f5d79d7699ec7e2a805a25ca0fca2b"><td class="mdescLeft">&#160;</td><td class="mdescRight">Performs perspective transformation on an image interpolating with the NEAREAST NEIGHBOUR method.  <a href="#ab8f5d79d7699ec7e2a805a25ca0fca2b">More...</a><br /></td></tr>
<tr class="separator:ab8f5d79d7699ec7e2a805a25ca0fca2b"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a5dba6d401b54fd02d20a2ba246668d93"><td class="memItemLeft" align="right" valign="top">__kernel void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="warp__perspective_8cl.xhtml#a5dba6d401b54fd02d20a2ba246668d93">warp_perspective_bilinear</a> (__global uchar *in_ptr, uint in_stride_x, uint in_step_x, uint in_stride_y, uint in_step_y, uint in_offset_first_element_in_bytes, __global uchar *out_ptr, uint out_stride_x, uint out_step_x, uint out_stride_y, uint out_step_y, uint out_offset_first_element_in_bytes, const int width, const int height)</td></tr>
<tr class="memdesc:a5dba6d401b54fd02d20a2ba246668d93"><td class="mdescLeft">&#160;</td><td class="mdescRight">Performs a perspective transform on an image interpolating with the BILINEAR method.  <a href="#a5dba6d401b54fd02d20a2ba246668d93">More...</a><br /></td></tr>
<tr class="separator:a5dba6d401b54fd02d20a2ba246668d93"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table>
<h2 class="groupheader">Function Documentation</h2>
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          <td class="memname">const float8 apply_perspective_transform </td>
          <td>(</td>
          <td class="paramtype">const float2&#160;</td>
          <td class="paramname"><em>coord</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">const float16&#160;</td>
          <td class="paramname"><em>mtx</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
  </td>
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<p>Transforms four 2D coordinates using the formula: </p>
<p>x0 = M[1][1] * x + M[1][2] * y + M[1][3] y0 = M[2][1] * x + M[2][2] * y + M[2][3] z0 = M[3][1] * x + M[3][2] * y + M[3][3]</p>
<p>(x0/z0,y0/z0)</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in]</td><td class="paramname">coord</td><td>2D coordinate to transform. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">mtx</td><td>perspective matrix</td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>a vector float8 containing four 2D transformed values. </dd></dl>

<p>Definition at line <a class="el" href="warp__perspective_8cl_source.xhtml#l00046">46</a> of file <a class="el" href="warp__perspective_8cl_source.xhtml">warp_perspective.cl</a>.</p>

<p>Referenced by <a class="el" href="warp__perspective_8cl_source.xhtml#l00119">warp_perspective_bilinear()</a>, and <a class="el" href="warp__perspective_8cl_source.xhtml#l00087">warp_perspective_nearest_neighbour()</a>.</p>
<div class="fragment"><div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;{</div><div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;    <span class="keyword">const</span> float4 in_x_coords = (float4)(coord.s0, 1 + coord.s0, 2 + coord.s0, 3 + coord.s0);</div><div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;    <span class="comment">// transform [z,z+1,z+2,z+3]</span></div><div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;    <span class="keyword">const</span> float4 z = (float4)mad(in_x_coords, (float4)(mtx.s2), mad((float4)(coord.s1), (float4)(mtx.s5), (float4)(mtx.s8)));</div><div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;    <span class="comment">// NOTE: Do not multiply x&amp;y by 1.f/Z as this will result in loss of accuracy and mismatches with VX reference implementation</span></div><div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;    <span class="comment">// transform [x,x+1,x+2,x+3]</span></div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;    <span class="keyword">const</span> float4 new_x = (float4)mad(in_x_coords, (float4)(mtx.s0), mad((float4)(coord.s1), (float4)(mtx.s3), (float4)(mtx.s6))) / z;</div><div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;    <span class="comment">// transform [y,y+1,y+2,y+3]</span></div><div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;    <span class="keyword">const</span> float4 new_y = (float4)mad(in_x_coords, (float4)(mtx.s1), mad((float4)(coord.s1), (float4)(mtx.s4), (float4)(mtx.s7))) / z;</div><div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;    <span class="keywordflow">return</span> (float8)(new_x.s0, new_y.s0, new_x.s1, new_y.s1, new_x.s2, new_y.s2, new_x.s3, new_y.s3);</div><div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;}</div></div><!-- fragment -->
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      <table class="memname">
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          <td class="memname">const float16 build_perspective_mtx </td>
          <td>(</td>
          <td class="paramname"></td><td>)</td>
          <td></td>
        </tr>
      </table>
  </td>
  <td class="mlabels-right">
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<p>Returns the perspective matrix. </p>

<p>Definition at line <a class="el" href="warp__perspective_8cl_source.xhtml#l00028">28</a> of file <a class="el" href="warp__perspective_8cl_source.xhtml">warp_perspective.cl</a>.</p>

<p>Referenced by <a class="el" href="warp__perspective_8cl_source.xhtml#l00119">warp_perspective_bilinear()</a>, and <a class="el" href="warp__perspective_8cl_source.xhtml#l00087">warp_perspective_nearest_neighbour()</a>.</p>
<div class="fragment"><div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;{</div><div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;    <span class="keywordflow">return</span> (float16)(MAT0, MAT1, MAT2, MAT3, MAT4, MAT5, MAT6, MAT7, MAT8, 0, 0, 0, (float4)0);</div><div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;}</div></div><!-- fragment -->
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          <td class="memname">__kernel void warp_perspective_bilinear </td>
          <td>(</td>
          <td class="paramtype">__global uchar *&#160;</td>
          <td class="paramname"><em>in_ptr</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_stride_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_step_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_stride_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_step_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_offset_first_element_in_bytes</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">__global uchar *&#160;</td>
          <td class="paramname"><em>out_ptr</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_stride_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_step_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_stride_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_step_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_offset_first_element_in_bytes</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">const int&#160;</td>
          <td class="paramname"><em>width</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">const int&#160;</td>
          <td class="paramname"><em>height</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">

<p>Performs a perspective transform on an image interpolating with the BILINEAR method. </p>
<p>Input and output are single channel U8.</p>
<dl class="section attention"><dt>Attention</dt><dd>The matrix coefficients need to be passed at compile time:<br />
const char build_options [] = "-DMAT0=1 -DMAT1=2 -DMAT2=3 -DMAT3=4 -DMAT4=5 -DMAT5=6 -DMAT6=7 -DMAT7=8 -DMAT8=9"<br />
clBuildProgram( program, 0, NULL, build_options, NULL, NULL);</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in]</td><td class="paramname">in_ptr</td><td>Pointer to the source image. Supported data types: U8. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_stride_x</td><td>Stride of the source image in X dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_step_x</td><td>in_stride_x * number of elements along X processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_stride_y</td><td>Stride of the source image in Y dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_step_y</td><td>in_stride_y * number of elements along Y processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_offset_first_element_in_bytes</td><td>Offset of the first element in the source image </td></tr>
    <tr><td class="paramdir">[out]</td><td class="paramname">out_ptr</td><td>Pointer to the destination image. Supported data types: U8. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_stride_x</td><td>Stride of the destination image in X dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_step_x</td><td>out_stride_x * number of elements along X processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_stride_y</td><td>Stride of the destination image in Y dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_step_y</td><td>out_stride_y * number of elements along Y processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_offset_first_element_in_bytes</td><td>Offset of the first element in the destination image </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">width</td><td>Width of the destination image </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">height</td><td>Height of the destination image </td></tr>
  </table>
  </dd>
</dl>

<p>Definition at line <a class="el" href="warp__perspective_8cl_source.xhtml#l00119">119</a> of file <a class="el" href="warp__perspective_8cl_source.xhtml">warp_perspective.cl</a>.</p>

<p>References <a class="el" href="warp__perspective_8cl_source.xhtml#l00046">apply_perspective_transform()</a>, <a class="el" href="warp__helpers_8h_source.xhtml#l00135">bilinear_interpolate()</a>, <a class="el" href="warp__perspective_8cl_source.xhtml#l00028">build_perspective_mtx()</a>, <a class="el" href="helpers_8h_source.xhtml#l00104">CONVERT_TO_IMAGE_STRUCT</a>, <a class="el" href="helpers_8h_source.xhtml#l00107">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a>, <a class="el" href="warp__helpers_8h_source.xhtml#l00067">get_current_coords()</a>, and <a class="el" href="helpers_8h_source.xhtml#l00144">Image::ptr</a>.</p>
<div class="fragment"><div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;{</div><div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;    <a class="code" href="struct_image.xhtml">Image</a> in  = <a class="code" href="helpers_8h.xhtml#a4334a4a76f8e9628c0fb9e1acf616e2a">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a>(in);</div><div class="line"><a name="l00126"></a><span class="lineno">  126</span>&#160;    <a class="code" href="struct_image.xhtml">Image</a> out = <a class="code" href="helpers_8h.xhtml#aebe814363556c244be043b13e7969197">CONVERT_TO_IMAGE_STRUCT</a>(out);</div><div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;    vstore4(<a class="code" href="warp__helpers_8h.xhtml#abea9f226daf3e0ad741d03cf7417d353">bilinear_interpolate</a>(&amp;in, <a class="code" href="warp__perspective_8cl.xhtml#a2791d623c1dbcf7e7111b8ff1b7daeeb">apply_perspective_transform</a>(<a class="code" href="warp__helpers_8h.xhtml#a4caaeeb51ea58015267a9974675226d1">get_current_coords</a>(), <a class="code" href="warp__perspective_8cl.xhtml#aa02a47b9dfa96a2705d5c77044a40048">build_perspective_mtx</a>()), width, height), 0, out.<a class="code" href="struct_image.xhtml#acf52c23cbd7424606c10a606524e3e32">ptr</a>);</div><div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;}</div><div class="ttc" id="helpers_8h_xhtml_a4334a4a76f8e9628c0fb9e1acf616e2a"><div class="ttname"><a href="helpers_8h.xhtml#a4334a4a76f8e9628c0fb9e1acf616e2a">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a></div><div class="ttdeci">#define CONVERT_TO_IMAGE_STRUCT_NO_STEP(name)</div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00107">helpers.h:107</a></div></div>
<div class="ttc" id="warp__perspective_8cl_xhtml_a2791d623c1dbcf7e7111b8ff1b7daeeb"><div class="ttname"><a href="warp__perspective_8cl.xhtml#a2791d623c1dbcf7e7111b8ff1b7daeeb">apply_perspective_transform</a></div><div class="ttdeci">const float8 apply_perspective_transform(const float2 coord, const float16 mtx)</div><div class="ttdoc">Transforms four 2D coordinates using the formula: </div><div class="ttdef"><b>Definition:</b> <a href="warp__perspective_8cl_source.xhtml#l00046">warp_perspective.cl:46</a></div></div>
<div class="ttc" id="helpers_8h_xhtml_aebe814363556c244be043b13e7969197"><div class="ttname"><a href="helpers_8h.xhtml#aebe814363556c244be043b13e7969197">CONVERT_TO_IMAGE_STRUCT</a></div><div class="ttdeci">#define CONVERT_TO_IMAGE_STRUCT(name)</div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00104">helpers.h:104</a></div></div>
<div class="ttc" id="warp__perspective_8cl_xhtml_aa02a47b9dfa96a2705d5c77044a40048"><div class="ttname"><a href="warp__perspective_8cl.xhtml#aa02a47b9dfa96a2705d5c77044a40048">build_perspective_mtx</a></div><div class="ttdeci">const float16 build_perspective_mtx()</div><div class="ttdoc">Returns the perspective matrix. </div><div class="ttdef"><b>Definition:</b> <a href="warp__perspective_8cl_source.xhtml#l00028">warp_perspective.cl:28</a></div></div>
<div class="ttc" id="struct_image_xhtml"><div class="ttname"><a href="struct_image.xhtml">Image</a></div><div class="ttdoc">Structure to hold Image information. </div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00142">helpers.h:142</a></div></div>
<div class="ttc" id="struct_image_xhtml_acf52c23cbd7424606c10a606524e3e32"><div class="ttname"><a href="struct_image.xhtml#acf52c23cbd7424606c10a606524e3e32">Image::ptr</a></div><div class="ttdeci">__global uchar * ptr</div><div class="ttdoc">Pointer to the starting postion of the buffer. </div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00144">helpers.h:144</a></div></div>
<div class="ttc" id="warp__helpers_8h_xhtml_a4caaeeb51ea58015267a9974675226d1"><div class="ttname"><a href="warp__helpers_8h.xhtml#a4caaeeb51ea58015267a9974675226d1">get_current_coords</a></div><div class="ttdeci">const float2 get_current_coords()</div><div class="ttdoc">Returns the current thread coordinates. </div><div class="ttdef"><b>Definition:</b> <a href="warp__helpers_8h_source.xhtml#l00067">warp_helpers.h:67</a></div></div>
<div class="ttc" id="warp__helpers_8h_xhtml_abea9f226daf3e0ad741d03cf7417d353"><div class="ttname"><a href="warp__helpers_8h.xhtml#abea9f226daf3e0ad741d03cf7417d353">bilinear_interpolate</a></div><div class="ttdeci">const DATA_TYPE4 bilinear_interpolate(const Image *in, const float8 coords, const float width, const float height)</div><div class="ttdoc">Computes the bilinear interpolation for each set of coordinates in the vector coords and returns the ...</div><div class="ttdef"><b>Definition:</b> <a href="warp__helpers_8h_source.xhtml#l00135">warp_helpers.h:135</a></div></div>
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<div class="memitem">
<div class="memproto">
      <table class="memname">
        <tr>
          <td class="memname">__kernel void warp_perspective_nearest_neighbour </td>
          <td>(</td>
          <td class="paramtype">__global uchar *&#160;</td>
          <td class="paramname"><em>in_ptr</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_stride_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_step_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_stride_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_step_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>in_offset_first_element_in_bytes</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">__global uchar *&#160;</td>
          <td class="paramname"><em>out_ptr</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_stride_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_step_x</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_stride_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_step_y</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">uint&#160;</td>
          <td class="paramname"><em>out_offset_first_element_in_bytes</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">const int&#160;</td>
          <td class="paramname"><em>width</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">const int&#160;</td>
          <td class="paramname"><em>height</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">

<p>Performs perspective transformation on an image interpolating with the NEAREAST NEIGHBOUR method. </p>
<p>Input and output are single channel U8.</p>
<p>This kernel performs perspective transform with a 3x3 Matrix M with this method of pixel coordinate translation: x0 = M[1][1] * x + M[1][2] * y + M[1][3] y0 = M[2][1] * x + M[2][2] * y + M[2][3] z0 = M[3][1] * x + M[3][2] * y + M[3][3]</p>
<p>output(x,y) = input(x0/z0,y0/z0)</p>
<dl class="section attention"><dt>Attention</dt><dd>The matrix coefficients need to be passed at compile time:<br />
const char build_options [] = "-DMAT0=1 -DMAT1=2 -DMAT2=3 -DMAT3=4 -DMAT4=5 -DMAT5=6 -DMAT6=7 -DMAT7=8 -DMAT8=9"<br />
clBuildProgram( program, 0, NULL, build_options, NULL, NULL);</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in]</td><td class="paramname">in_ptr</td><td>Pointer to the source image. Supported data types: U8. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_stride_x</td><td>Stride of the source image in X dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_step_x</td><td>in_stride_x * number of elements along X processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_stride_y</td><td>Stride of the source image in Y dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_step_y</td><td>in_stride_y * number of elements along Y processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">in_offset_first_element_in_bytes</td><td>Offset of the first element in the source image </td></tr>
    <tr><td class="paramdir">[out]</td><td class="paramname">out_ptr</td><td>Pointer to the destination image. Supported data types: U8. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_stride_x</td><td>Stride of the destination image in X dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_step_x</td><td>out_stride_x * number of elements along X processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_stride_y</td><td>Stride of the destination image in Y dimension (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_step_y</td><td>out_stride_y * number of elements along Y processed per work item (in bytes) </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">out_offset_first_element_in_bytes</td><td>Offset of the first element in the destination image </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">width</td><td>Width of the destination image </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">height</td><td>Height of the destination image </td></tr>
  </table>
  </dd>
</dl>

<p>Definition at line <a class="el" href="warp__perspective_8cl_source.xhtml#l00087">87</a> of file <a class="el" href="warp__perspective_8cl_source.xhtml">warp_perspective.cl</a>.</p>

<p>References <a class="el" href="warp__perspective_8cl_source.xhtml#l00046">apply_perspective_transform()</a>, <a class="el" href="warp__perspective_8cl_source.xhtml#l00028">build_perspective_mtx()</a>, <a class="el" href="warp__helpers_8h_source.xhtml#l00048">clamp_to_border()</a>, <a class="el" href="helpers_8h_source.xhtml#l00104">CONVERT_TO_IMAGE_STRUCT</a>, <a class="el" href="helpers_8h_source.xhtml#l00107">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a>, <a class="el" href="warp__helpers_8h_source.xhtml#l00067">get_current_coords()</a>, <a class="el" href="helpers_8h_source.xhtml#l00144">Image::ptr</a>, and <a class="el" href="warp__helpers_8h_source.xhtml#l00058">read_texels4()</a>.</p>
<div class="fragment"><div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;{</div><div class="line"><a name="l00093"></a><span class="lineno">   93</span>&#160;    <a class="code" href="struct_image.xhtml">Image</a> in  = <a class="code" href="helpers_8h.xhtml#a4334a4a76f8e9628c0fb9e1acf616e2a">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a>(in);</div><div class="line"><a name="l00094"></a><span class="lineno">   94</span>&#160;    <a class="code" href="struct_image.xhtml">Image</a> out = <a class="code" href="helpers_8h.xhtml#aebe814363556c244be043b13e7969197">CONVERT_TO_IMAGE_STRUCT</a>(out);</div><div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;    vstore4(<a class="code" href="warp__helpers_8h.xhtml#aba42442a4c991cdbb52727fa370676f1">read_texels4</a>(&amp;in, convert_int8_rtn(<a class="code" href="warp__helpers_8h.xhtml#adbdf2ca9e8fe0b67f9359929ef743126">clamp_to_border</a>(<a class="code" href="warp__perspective_8cl.xhtml#a2791d623c1dbcf7e7111b8ff1b7daeeb">apply_perspective_transform</a>(<a class="code" href="warp__helpers_8h.xhtml#a4caaeeb51ea58015267a9974675226d1">get_current_coords</a>(), <a class="code" href="warp__perspective_8cl.xhtml#aa02a47b9dfa96a2705d5c77044a40048">build_perspective_mtx</a>()), width, height))), 0, out.<a class="code" href="struct_image.xhtml#acf52c23cbd7424606c10a606524e3e32">ptr</a>);</div><div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;}</div><div class="ttc" id="warp__helpers_8h_xhtml_adbdf2ca9e8fe0b67f9359929ef743126"><div class="ttname"><a href="warp__helpers_8h.xhtml#adbdf2ca9e8fe0b67f9359929ef743126">clamp_to_border</a></div><div class="ttdeci">const float8 clamp_to_border(float8 coords, const float width, const float height)</div><div class="ttdoc">Clamps the given coordinates to the borders. </div><div class="ttdef"><b>Definition:</b> <a href="warp__helpers_8h_source.xhtml#l00048">warp_helpers.h:48</a></div></div>
<div class="ttc" id="helpers_8h_xhtml_a4334a4a76f8e9628c0fb9e1acf616e2a"><div class="ttname"><a href="helpers_8h.xhtml#a4334a4a76f8e9628c0fb9e1acf616e2a">CONVERT_TO_IMAGE_STRUCT_NO_STEP</a></div><div class="ttdeci">#define CONVERT_TO_IMAGE_STRUCT_NO_STEP(name)</div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00107">helpers.h:107</a></div></div>
<div class="ttc" id="warp__perspective_8cl_xhtml_a2791d623c1dbcf7e7111b8ff1b7daeeb"><div class="ttname"><a href="warp__perspective_8cl.xhtml#a2791d623c1dbcf7e7111b8ff1b7daeeb">apply_perspective_transform</a></div><div class="ttdeci">const float8 apply_perspective_transform(const float2 coord, const float16 mtx)</div><div class="ttdoc">Transforms four 2D coordinates using the formula: </div><div class="ttdef"><b>Definition:</b> <a href="warp__perspective_8cl_source.xhtml#l00046">warp_perspective.cl:46</a></div></div>
<div class="ttc" id="helpers_8h_xhtml_aebe814363556c244be043b13e7969197"><div class="ttname"><a href="helpers_8h.xhtml#aebe814363556c244be043b13e7969197">CONVERT_TO_IMAGE_STRUCT</a></div><div class="ttdeci">#define CONVERT_TO_IMAGE_STRUCT(name)</div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00104">helpers.h:104</a></div></div>
<div class="ttc" id="warp__perspective_8cl_xhtml_aa02a47b9dfa96a2705d5c77044a40048"><div class="ttname"><a href="warp__perspective_8cl.xhtml#aa02a47b9dfa96a2705d5c77044a40048">build_perspective_mtx</a></div><div class="ttdeci">const float16 build_perspective_mtx()</div><div class="ttdoc">Returns the perspective matrix. </div><div class="ttdef"><b>Definition:</b> <a href="warp__perspective_8cl_source.xhtml#l00028">warp_perspective.cl:28</a></div></div>
<div class="ttc" id="struct_image_xhtml"><div class="ttname"><a href="struct_image.xhtml">Image</a></div><div class="ttdoc">Structure to hold Image information. </div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00142">helpers.h:142</a></div></div>
<div class="ttc" id="struct_image_xhtml_acf52c23cbd7424606c10a606524e3e32"><div class="ttname"><a href="struct_image.xhtml#acf52c23cbd7424606c10a606524e3e32">Image::ptr</a></div><div class="ttdeci">__global uchar * ptr</div><div class="ttdoc">Pointer to the starting postion of the buffer. </div><div class="ttdef"><b>Definition:</b> <a href="helpers_8h_source.xhtml#l00144">helpers.h:144</a></div></div>
<div class="ttc" id="warp__helpers_8h_xhtml_aba42442a4c991cdbb52727fa370676f1"><div class="ttname"><a href="warp__helpers_8h.xhtml#aba42442a4c991cdbb52727fa370676f1">read_texels4</a></div><div class="ttdeci">const DATA_TYPE4 read_texels4(const Image *in, const int8 coords)</div><div class="ttdoc">Reads four texels from the input image. </div><div class="ttdef"><b>Definition:</b> <a href="warp__helpers_8h_source.xhtml#l00058">warp_helpers.h:58</a></div></div>
<div class="ttc" id="warp__helpers_8h_xhtml_a4caaeeb51ea58015267a9974675226d1"><div class="ttname"><a href="warp__helpers_8h.xhtml#a4caaeeb51ea58015267a9974675226d1">get_current_coords</a></div><div class="ttdeci">const float2 get_current_coords()</div><div class="ttdoc">Returns the current thread coordinates. </div><div class="ttdef"><b>Definition:</b> <a href="warp__helpers_8h_source.xhtml#l00067">warp_helpers.h:67</a></div></div>
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